Host Environment Commands › ADDRESS EPI Commands › EPI PEEK—Display Screen Buffer in Hexadecimal

EPI PEEK—Display Screen Buffer in Hexadecimal

Use this command to display the contents of the virtual terminal screen buffer in hexadecimal format. EPI displays 16 hexadecimal bytes for each output line except for row 0 of the screen. PEEK under EPI does not read the contents of row 0.

Usually, you issue this command to interrogate 3278 host attribute bytes. The PEEK command runs synchronously in AOF rules and returns data to the external data queue. The command returns buffer code in EBCDIC format; values ranging from X'20' through X'3F' are attribute bytes. You can read the screen more easily using the RDSCREEN and RDSCRROW commands of the EPI (described later in this chapter).

This command has the following format:

ADDRESS EPI "PEEK keywords"
/* You must specify a value for each keyword.   */
  {termname|*}
  {row}
  {col}
  {length}

termname

Defines the virtual terminal for which you want to display buffer contents.

*

Specifies the current terminal defined through the SETTERM command.

row

Identifies the number of the screen row where capturing of buffer contents begins.

col

Identifies the number of the screen column where capturing of buffer contents begins.

length

Defines the number of lines from the screen buffer to be displayed.

Example: EPI PEEK

Suppose that you issue this PEEK command:

PEEK TERM4 22 1 30

You receive this output:

24 D9 C5 C1 C4 E8 20 00 00 00 00 00 00 00 00 00 *.READY..........*
00 00 00 00 00 00 00 00 00 00 00 00 00 00

This example shows the beginning of the TSO READY message on terminal TERM4. The first number, 24, is a high-intensity unprotected attribute byte. The five characters following it are READY in 3278 buffer code. The number following that, 20, is a low-intensity unprotected attribute byte.